1. Field of the Invention
The present invention relates to a computer program product, system, and method for rebuilding damaged areas of a volume table using a volume data set.
2. Description of the Related Art
In certain computing environments, multiple host systems may configure data sets in volumes configured in a storage system, such as interconnected storage devices, e.g., a Direct Access Storage Device (DASD), Redundant Array of Independent Disks (RAID), Just a Bunch of Disks (JBOD), etc. Data sets are comprised of extents, which may comprise any grouping of tracks and data storage units. The Z/OS® operating system from International Business Machines Corporation (“IBM”) has a Volume Table of Contents (VTOC) to provide information on data sets of extents configured in the volume, where the VTOC indicates the location of tracks, extents, and data sets for a volume in storage. For Virtual Storage Access Method (VSAM) data sets that are indexed by keys, the z/OS operating system provides VSAM volume data sets (VVDS) having records providing metadata for VSAM indexed data sets. The VTOC has information on non-VSAM data sets in the volume. The records in the VVDS comprise a VSAM Volume Record (VVR) providing metadata for VSAM data sets and non-VSAM Volume Records (NVR) providing metadata for non-VSAM or non-indexed data sets. (Z/OS is a registered trademark of IBM in the United States and other countries) The VSAM access method for data sets was introduced by International Business Machines Corporation.
Data records in the volume table providing information on the allocation of extents to data sets in a volume may become corrupted such as by overlaying data set records or by write operations that corrupt the data. Data corruption may be the result of program bugs, user errors, or Original Equipment Manufacturer (OEM) interactions. This corruption often goes undetected until applications encounter errors due to incorrect or missing data. This type of corruption can expand throughout the volume the longer this error remains undetected, leading to system outages and lengthy recovery times.
Further, if the data set records in the VTOC become overlaid and corrupt, the actual data sets on the volume may still be intact, but they cannot be referenced without the metadata in the VTOC. If one track of the VTOC is overwritten, numerous data sets on that volume become inaccessible, resulting in a critical impact error.